W inifred J. Marquart is an American billionaire heiress and a member of the Johnson family, which owns S.C. Johnson & Son, a massive privately held consumer goods company. She is the daughter of Samuel Curtis Johnson Jr. and the great-great-granddaughter of the company's founder. S.C. Johnson is known for household brands like Windex, Pledge, Glade, and Ziploc.

Unlike her siblings Fisk Johnson, Helen Johnson-Leipold, and S. Curtis Johnson, who have taken active executive roles in the family's various businesses, Winifred has largely stayed out of the corporate operations. Instead, she focuses on philanthropy and family governance, serving as the president of the Johnson Family Foundation. She is a graduate of Cornell University and, along with her siblings, has made significant donations to her alma mater, including a $150 million gift to the College of Business.